[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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[b06ca36] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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[673b0d8] | 4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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| 5 | %general-entities;
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| 6 | ]>
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[1f7ca93] | 7 |
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[9652249] | 8 | <sect1 id="ch-tools-gcc-pass2" role="wrap">
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[1f7ca93] | 9 | <?dbhtml filename="gcc-pass2.html"?>
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| 10 |
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[e747759] | 11 | <sect1info condition="script">
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| 12 | <productname>gcc</productname>
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| 13 | <productnumber>&gcc-version;</productnumber>
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| 14 | <address>&gcc-url;</address>
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| 15 | </sect1info>
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| 16 |
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[1f7ca93] | 17 | <title>GCC-&gcc-version; - Pass 2</title>
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| 18 |
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| 19 | <indexterm zone="ch-tools-gcc-pass2">
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| 20 | <primary sortas="a-GCC">GCC</primary>
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| 21 | <secondary>tools, pass 2</secondary>
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| 22 | </indexterm>
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| 23 |
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| 24 | <sect2 role="package">
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| 25 | <title/>
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[bc82645e] | 26 |
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[d9441360] | 27 | <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
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[1f7ca93] | 28 | href="../chapter06/gcc.xml"
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| 29 | xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
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[81fd230] | 30 |
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[1f7ca93] | 31 | <segmentedlist>
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| 32 | <segtitle>&buildtime;</segtitle>
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| 33 | <segtitle>&diskspace;</segtitle>
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[73aedd1d] | 34 |
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[1f7ca93] | 35 | <seglistitem>
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[e4a5635] | 36 | <seg>&gcc-ch5p2-sbu;</seg>
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| 37 | <seg>&gcc-ch5p2-du;</seg>
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[1f7ca93] | 38 | </seglistitem>
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| 39 | </segmentedlist>
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[73aedd1d] | 40 |
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[1f7ca93] | 41 | </sect2>
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[9652249] | 42 |
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[1f7ca93] | 43 | <sect2 role="installation">
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[4e82d47] | 44 | <title>Installation of GCC</title>
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[73aedd1d] | 45 |
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[1a3e6a3] | 46 | <para>Our first build of GCC has installed a couple of internal system
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| 47 | headers. Normally one of them, <filename>limits.h</filename> will in turn
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| 48 | include the corresponding system <filename>limits.h</filename> header, in
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| 49 | this case, <filename>/tools/include/limits.h</filename>. However, at the
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| 50 | time of the first build of gcc <filename>/tools/include/limits.h</filename>
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| 51 | did not exist, so the internal header that GCC installed is a partial,
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| 52 | self-contained file and does not include the extended features of the
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| 53 | system header. This was adequate for building the temporary libc, but this
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| 54 | build of GCC now requires the full internal header. Create a full version
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| 55 | of the internal header using a command that is identical to what the GCC
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| 56 | build system does in normal circumstances:</para>
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| 57 |
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| 58 | <screen><userinput remap="pre">cat gcc/limitx.h gcc/glimits.h gcc/limity.h > \
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| 59 | `dirname $($LFS_TGT-gcc -print-libgcc-file-name)`/include-fixed/limits.h</userinput></screen>
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[6206f72] | 60 | <!--
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[f6fe500] | 61 | <para>For x86 machines, the limited number of registers is a bottleneck
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[6206f72] | 62 | for the system. Free one up by not using a frame pointer that is not
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[f6fe500] | 63 | needed:</para>
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[2e02c35] | 64 |
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[8b69ae4] | 65 | <screen><userinput remap="pre">case `uname -m` in
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| 66 | i?86) sed -i 's/^T_CFLAGS =$/& -fomit-frame-pointer/' gcc/Makefile.in ;;
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| 67 | esac</userinput></screen>
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[6206f72] | 68 | -->
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[1a3e6a3] | 69 | <para>Once again, change the location of GCC's default dynamic linker to
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| 70 | use the one installed in <filename
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| 71 | class="directory">/tools</filename>.</para>
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[b0a4c9a] | 72 |
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[6e88633] | 73 | <screen><userinput remap="pre">for file in \
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| 74 | $(find gcc/config -name linux64.h -o -name linux.h -o -name sysv4.h)
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[b0a4c9a] | 75 | do
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| 76 | cp -uv $file{,.orig}
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| 77 | sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&@g' \
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[3dc9543] | 78 | -e 's@/usr@/tools@g' $file.orig > $file
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[4e82d47] | 79 | echo '
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[c8f104d] | 80 | #undef STANDARD_STARTFILE_PREFIX_1
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| 81 | #undef STANDARD_STARTFILE_PREFIX_2
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[1a3e6a3] | 82 | #define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/"
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[4e82d47] | 83 | #define STANDARD_STARTFILE_PREFIX_2 ""' >> $file
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[b0a4c9a] | 84 | touch $file.orig
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| 85 | done</userinput></screen>
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| 86 |
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[4916842] | 87 | <para>As in the first build of GCC it requires the GMP, MPFR and MPC
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| 88 | packages. Unpack the tarballs and move them into the required directory
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| 89 | names:</para>
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[c49647b1] | 90 |
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[ee648fd] | 91 | <screen><userinput remap="pre">tar -xf ../mpfr-&mpfr-version;.tar.xz
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[e311865] | 92 | mv -v mpfr-&mpfr-version; mpfr
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[ee648fd] | 93 | tar -xf ../gmp-&gmp-version;.tar.xz
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| 94 | mv -v gmp-&gmp-extracted-version; gmp
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| 95 | tar -xf ../mpc-&mpc-version;.tar.gz
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[4916842] | 96 | mv -v mpc-&mpc-version; mpc</userinput></screen>
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[c49647b1] | 97 |
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[1f7ca93] | 98 | <para>Create a separate build directory again:</para>
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[73aedd1d] | 99 |
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[0445a3d] | 100 | <screen><userinput remap="pre">mkdir -v ../gcc-build
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[73aedd1d] | 101 | cd ../gcc-build</userinput></screen>
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| 102 |
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[1f7ca93] | 103 | <para>Before starting to build GCC, remember to unset any environment
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| 104 | variables that override the default optimization flags.</para>
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[81fd230] | 105 |
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[1f7ca93] | 106 | <para>Now prepare GCC for compilation:</para>
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[73aedd1d] | 107 |
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[1ff8d777] | 108 | <screen><userinput remap="configure">CC=$LFS_TGT-gcc \
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[6458e31] | 109 | CXX=$LFS_TGT-g++ \
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| 110 | AR=$LFS_TGT-ar \
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| 111 | RANLIB=$LFS_TGT-ranlib \
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| 112 | ../gcc-&gcc-version;/configure \
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| 113 | --prefix=/tools \
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| 114 | --with-local-prefix=/tools \
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| 115 | --with-native-system-header-dir=/tools/include \
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| 116 | --enable-clocale=gnu \
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| 117 | --enable-shared \
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| 118 | --enable-threads=posix \
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| 119 | --enable-__cxa_atexit \
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| 120 | --enable-languages=c,c++ \
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| 121 | --disable-libstdcxx-pch \
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| 122 | --disable-multilib \
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| 123 | --disable-bootstrap \
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[8aa7fde] | 124 | --disable-libgomp</userinput></screen>
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[73aedd1d] | 125 |
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[1f7ca93] | 126 | <variablelist>
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| 127 | <title>The meaning of the new configure options:</title>
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| 128 |
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| 129 | <varlistentry>
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| 130 | <term><parameter>--enable-clocale=gnu</parameter></term>
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| 131 | <listitem>
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| 132 | <para>This option ensures the correct locale model is selected
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| 133 | for the C++ libraries under all circumstances. If the configure
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| 134 | script finds the <emphasis>de_DE</emphasis> locale installed,
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| 135 | it will select the correct gnu locale model. However, if the
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| 136 | <emphasis>de_DE</emphasis> locale is not installed, there is the
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| 137 | risk of building Application Binary Interface (ABI)-incompatible
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| 138 | C++ libraries because the incorrect generic locale model may be
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| 139 | selected.</para>
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| 140 | </listitem>
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| 141 | </varlistentry>
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| 142 |
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| 143 | <varlistentry>
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| 144 | <term><parameter>--enable-threads=posix</parameter></term>
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| 145 | <listitem>
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| 146 | <para>This enables C++ exception handling for multi-threaded code.</para>
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| 147 | </listitem>
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| 148 | </varlistentry>
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| 149 |
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| 150 | <varlistentry>
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| 151 | <term><parameter>--enable-__cxa_atexit</parameter></term>
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| 152 | <listitem>
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| 153 | <para>This option allows use of <function>__cxa_atexit</function>,
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| 154 | rather than <function>atexit</function>, to register C++ destructors
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| 155 | for local statics and global objects. This option is essential for
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| 156 | fully standards-compliant handling of destructors. It also affects
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| 157 | the C++ ABI, and therefore results in C++ shared libraries and C++
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| 158 | programs that are interoperable with other Linux distributions.</para>
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| 159 | </listitem>
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| 160 | </varlistentry>
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| 161 |
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| 162 | <varlistentry>
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| 163 | <term><parameter>--enable-languages=c,c++</parameter></term>
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| 164 | <listitem>
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| 165 | <para>This option ensures that both the C and C++ compilers are
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| 166 | built.</para>
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| 167 | </listitem>
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| 168 | </varlistentry>
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| 169 |
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| 170 | <varlistentry>
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| 171 | <term><parameter>--disable-libstdcxx-pch</parameter></term>
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| 172 | <listitem>
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| 173 | <para>Do not build the pre-compiled header (PCH) for
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| 174 | <filename class="libraryfile">libstdc++</filename>. It takes up a
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| 175 | lot of space, and we have no use for it.</para>
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| 176 | </listitem>
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| 177 | </varlistentry>
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| 178 |
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[b0a4c9a] | 179 | <varlistentry>
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| 180 | <term><parameter>--disable-bootstrap</parameter></term>
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| 181 | <listitem>
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[fe6ca49] | 182 | <para>For native builds of GCC, the default is to do a "bootstrap"
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| 183 | build. This does not just compile GCC, but compiles it several times.
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| 184 | It uses the programs compiled in a first round to compile itself a
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[07312f6] | 185 | second time, and then again a third time. The second and third
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| 186 | iterations are compared to make sure it can reproduce itself
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| 187 | flawlessly. This also implies that it was compiled correctly.
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| 188 | However, the LFS build method should provide a solid compiler
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[2ca8941] | 189 | without the need to bootstrap each time.</para>
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[b0a4c9a] | 190 | </listitem>
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| 191 | </varlistentry>
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| 192 |
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[1f7ca93] | 193 | </variablelist>
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| 194 |
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| 195 | <para>Compile the package:</para>
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[73aedd1d] | 196 |
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[bd7123b] | 197 | <screen><userinput remap="make">make</userinput></screen>
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[73aedd1d] | 198 |
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[1f7ca93] | 199 | <para>Install the package:</para>
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[73aedd1d] | 200 |
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[0445a3d] | 201 | <screen><userinput remap="install">make install</userinput></screen>
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[73aedd1d] | 202 |
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[4e82d47] | 203 | <para>As a finishing touch, create a symlink. Many programs and scripts
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| 204 | run <command>cc</command> instead of <command>gcc</command>, which is
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| 205 | used to keep programs generic and therefore usable on all kinds of UNIX
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| 206 | systems where the GNU C compiler is not always installed. Running
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| 207 | <command>cc</command> leaves the system administrator free to decide
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| 208 | which C compiler to install:</para>
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| 209 |
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[5cef314] | 210 | <screen><userinput remap="install">ln -sv gcc /tools/bin/cc</userinput></screen>
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[4e82d47] | 211 |
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| 212 | <caution>
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| 213 | <para>At this point, it is imperative to stop and ensure that the basic
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| 214 | functions (compiling and linking) of the new toolchain are working as
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| 215 | expected. To perform a sanity check, run the following commands:</para>
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| 216 |
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| 217 | <screen><userinput>echo 'main(){}' > dummy.c
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| 218 | cc dummy.c
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| 219 | readelf -l a.out | grep ': /tools'</userinput></screen>
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| 220 |
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| 221 | <para>If everything is working correctly, there should be no errors,
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| 222 | and the output of the last command will be of the form:</para>
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| 223 |
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[dc96e56] | 224 | <screen><computeroutput>[Requesting program interpreter: /tools/lib/ld-linux.so.2]</computeroutput></screen>
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[4e82d47] | 225 |
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| 226 | <para>Note that <filename class="directory">/tools/lib</filename>, or
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| 227 | <filename class="directory">/tools/lib64</filename> for 64-bit machines
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| 228 | appears as the prefix of the dynamic linker.</para>
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| 229 |
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| 230 | <para>If the output is not shown as above or there was no output at all,
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| 231 | then something is wrong. Investigate and retrace the steps to find out
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| 232 | where the problem is and correct it. This issue must be resolved before
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| 233 | continuing on. First, perform the sanity check again, using
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| 234 | <command>gcc</command> instead of <command>cc</command>. If this works,
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| 235 | then the <filename class="symlink">/tools/bin/cc</filename> symlink is
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| 236 | missing. Install the symlink as per above.
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| 237 | Next, ensure that the <envar>PATH</envar> is correct. This
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| 238 | can be checked by running <command>echo $PATH</command> and verifying that
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| 239 | <filename class="directory">/tools/bin</filename> is at the head of the
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| 240 | list. If the <envar>PATH</envar> is wrong it could mean that you are not
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| 241 | logged in as user <systemitem class="username">lfs</systemitem> or that
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| 242 | something went wrong back in <xref linkend="ch-tools-settingenviron"
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| 243 | role="."/></para>
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| 244 |
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| 245 | <para>Once all is well, clean up the test files:</para>
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| 246 |
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| 247 | <screen><userinput>rm -v dummy.c a.out</userinput></screen>
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| 248 |
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| 249 | </caution>
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[73aedd1d] | 250 |
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[1f7ca93] | 251 | </sect2>
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[bc82645e] | 252 |
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[1f7ca93] | 253 | <sect2 role="content">
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| 254 | <title/>
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[81fd230] | 255 |
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[1f7ca93] | 256 | <para>Details on this package are located in
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| 257 | <xref linkend="contents-gcc" role="."/></para>
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[81fd230] | 258 |
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[1f7ca93] | 259 | </sect2>
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| 260 |
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| 261 | </sect1>
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